Section 57A. In any city or town which accepts the provisions of this section notwithstanding the provisions of section fifty-seven, if a bill for real estate or personal property taxes, in an amount not in excess of twenty-five dollars, remains unpaid after November first of the fiscal year in which it is payable, or after the thirtieth day after the date on which the bill for such tax was mailed, if mailed after October first, interest at the rate of fourteen per cent per annum computed from October first, or from the date the bill for such tax was mailed, if mailed after October first, shall be paid on such unpaid tax.